Historically, television services have been comprised of analog broadcast audio and video signals. Cable television systems now receive broadcasts and retransmit them with other programming to subscribers over land-line networks, typically comprising fiber optic cable and/or coaxial cable. With the recent advent of digital transmission technology, cable television systems are now capable of providing much more than the traditional analog broadcast video. In addition, two-way and advanced one-way communications between a subscriber and a cable system headend are now possible.
In implementing enhanced programming, the home communication terminal (“HCT”), otherwise known as the settop box, has become an important computing device for accessing video services and navigating a subscriber through a maze of services available. In addition to supporting traditional analog broadcast video functionality, digital HCTs (or “DHCTs”) now also support an increasing number of services which are not analog, but rather digital; are not basic broadcast, but rather two-way communication such as video-on-demand; and are not basic video, such as e-mail or web browsers. These are all in addition to the host of other television services which are increasingly being demanded by consumers, examples of which include audio and audio/visual programming, advanced navigation controls, impulse pay-per-view technology, and on-line commerce. In addition to the interactive services, the increased bandwidth available through a digital television system has made it possible for a subscriber to have access to hundreds, or even thousands, of channels and/or services. Thus, in order to provide these more powerful and complex features, the simple conventional channel abstractions need to be extended beyond those which have traditionally been provided.
Each HCT or DHCT (collectively hereinafter “DHCT”) is typically connected to a cable or satellite television network. The DHCTs generally include hardware and software necessary to provide the functionality of the digital television system at the client's site. Preferably, some of the software executed by a DHCT is downloaded and/or updated via the cable television network. Each DHCT typically includes a processor, communication components and memory, and is connected to a television or other display device, such as a personal computer. While many conventional DHCTs are stand-alone devices that are externally connected to a television, a DHCT and/or its functionality may be integrated into a television or personal computer, as will be appreciated by those of ordinary skill in the art.
Because many separate services may be offered by a single cable television service provider to each individual subscriber, including television viewing channels as well as other applications, there is a need for the DHCT to not only be able to provide each service that the cable television system provider offers but also be able to flexibly control access to services that are denoted as premium services. In addition, certain television programs can now be broadcast in advanced formats, such as in high definition television (HDTV) format; however, there is currently no mechanism for efficiently handling such advanced formats to effectively integrate them into systems which must also continue supporting older formats.